Rock crusher

ABSTRACT

A wedging ring carried in a groove in a bowl jams thread segments against a threaded portion of a bowl carrier which is pressed against a hardened ring by a frictional overload clamp. In turning the bowl relative to the bowl carrier, a manual, automatic or partially automatic drive actuates a pawl and ratchet drive. The crusher head supports an annular mantle held by a wedging ring and a self-tightening nut.

Unite States Patent 1191 1111 3,759,453 Johnson 1 Sept. 18, 1973 [5 ROCK CRUSHER r 3,337,143 8/1967 Johnson 241 215 Inventor: Louis W. J 3440 Franklin 3,539,118 11/1970 Kueneman 241/207 Blvd" Eugene Oreg' 97403 Primary Examiner-Granville Y. Custer, Jr. [22] Filed: Dec. 27, 11971 Attorney--Stephen W. Blore et al. [21] Appl. No.: 211,888

[57] ABSTRACT 52 us. (:1. 241/207, 241/286 A wedging ring carried in a groove in a bowl j [51] Int. Cl. 1302c 2/04 thread segments against a threaded Portion of a bowl [58] Field of Search 241/207, 203, 209, carrier which is Pressed against a hardened ring y a 1 241/214 215, 216, 286 293 frictional overload clamp. 1n turning the bowl relative to the bowl carrier, a manual, automatic or partially au- [56] References Cited tomatic drive actuates a pawl and ratchet drive. The UNITED STATES PATENTS crusher head supports an annular mantle held by a wedging ring and a self-tightening nut. 3,140,835 7/1964 Balmer et al. 2.41/286 3,250,478

5/1966 Olson 241/215 22 Claims, 12 Drawing Figures 1o 1 j 1* 95 I I B 1 I05 77, 1 130 I 67 43 79 5O 75 1 l 41 101 I I\ 1/ 1 \165 121- I 1 I3 11 123 27 119 1 H5 1 I I18 PATENIEUSEPWW 3.159.453

SHEET 2 OF 4 LOUIS W. JOHNSON INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS PATENTEBSEH 8M3 3,759,453

FIG.

LOUIS W. JOHNSON 4| INVENTQR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS PAIENIED EH 3.759.453

snmuuFa Jb1 .rxymx \wlwi LOUIS W. JOHNSON INVENTOR BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS ROCK CRUSI-IER DESCRIPTION This invention relates to an improved rock crusher, and more particularly to an improved rock crusher of the gyratory crusher head type.-

An object of the invention is to provide a new and improved rock crusher.

Another object of the invention is to provide a new and improved rock crusher of the gyratory crusher head type.

A further object of the invention is to provide a new and improved bowl mounting structure.

Another object of the invention is to provide a crusher wherein a bowl carries expandable thread segments which are wedged outwardly into threads of a bowl carrier to lock the bowl in adjusted position on the bowl carrier.

Another object of the invention is to provide a crusher in which a bowl carrier is mounted on a hardened annular way bolted to the frame. Another object of the invention is to provide a crusher wherein a bowl carrier is clamped by hard, low friction material so that it can rotate only under abnormally high forces.

Another object of the invention is to provide a crusher in which a bowl is clamped in adjusted position on a bowl carrier by Belleville washers.

Another object of the invention is to provide a crusher having a bowl relative to a bowl carrier by a pawl and ratchet mechanism driven by either a manual drive or by a fully or partially automatic drive.

Another object of the invention is to provide a rock crusher having a gyratory head on which a mantle is clamped by a self-tightening wedging ring screwed into a nut bolted to the top of the head.

In the drawings:

FIG. 1 is a side elevation view of an improved rock crusher forming one embodiment of the invention and partially broken away for convenience of illustration;

FIG. 2 is a plan view taken along line 2-2 of FIG. 1;

FIG. 3 is a fragmentary side elevational view of a portion of the rock crusher of FIG. 1;

FIG. 4 is an enlarged fragmentary vertical sectional view taken along lines 4-4 of FIG. 2;

FIG. 5 is an enlarged fragmentary vertical sectional view taken along lines 5-5 of FIG. 2; I

FIG. 6 is an enlarged, fragmentary top plan view of a bowladjusting mechanism;

FIG. 7 is an enlarged, fragmentary elevational view taken along line 7-7 of FIG. 6; I I

FIG. 8 is a horizontal sectional view taken along line 8-8 of FIG. 7;

FIG. 9 is a vertical sectional view taken along line 9-9 of FIG. 6;

FIG. 10 is a vertical sectional view taken along line 10-40 of FIG. 4;

FIG. 11 is a top plan view taken along line -11 of FIG. 10; and

I a crusher head 13 on thrust bearing 15 mounted on camming member 17 which, in turn, is rotatably supported on hearing 19 on inner shell 21 forming part of the frame 11. The camming member 17 is driven by a drive system 23 like that disclosed in my U.S. Pat. No. 3,337,143 and having a pulley 25 driven by a motor and belt drive (not shown), ajack shaft 27 and a pinion gear 29 rotating a ring gear 31 fixed to the bottom of the camming member 17. The crusher head is gyrated and rocked by the drive system and the camming member.

BOWL STRUCTURE MOUNTING SYSTEM A hardened V-shaped support ring or annular way 33 (FIG. 1) is attached by bolts 35 to a top flange 37 of the frame 11, the top flange 37 and the ring 33 forming a separable assembly. The flange 37 has a groove 39 aligning the bottom side of the V -shaped support ring 33 therein. The top surface of the V-shaped support ring 33 is shaped as a guideway for a bowl carrier 41 which has a grooved way fitting on the hardened support ring to prevent side play. The bowl carrier is part of an overall bowl structure, and can be considered as a nut, having internal threads 43 engaging male threads 45 of a segmented adjustment ring 47. Its segments slidably fit in notches in bowl or liner support 49 and support the bowl. The notches provide a splined fit between the segments and the bowl so that when the bowl is turned, as will be hereinafter described, the segments are carried with it.

l The ring 47 has six equal length segments (FIG. 2), but it may have more or less as desired. A bowl liner 51 (FIG. 1) is suspended below the how] 49 by strain rods 7 53 pivotally attached at one end to ears 55 on the back side of the liner 51, and passing up through holes 57 in the bowl 49, with nuts 59 locking them in place. Filler blocks 60 are interposed between liner 51 and bowl 49.

BOWL LOCKING SYSTEM Inside surface 61 of the adjustment ring 47 is inclined to properly fit against a segmented wedging ring, whose parts are hereinafter called wedges 63. As the wedges 63 are forced downward, by the action of double-acting cylinders 65 of a plurality of hydraulic thrusting units 66 (FIG. 4) and spring thrust units 67 (FIG. 5), the segmented adjustment ring 47 is expanded to force its threads 45 into tight engagement with the threads 43 of the bowl carrier 41. This removes all axial and radial clearances to form an extremely secure frictional lock, to prevent the bowl 49 from turningrelative. to the bowl carrier 41 during crushing operations. The bowl 49 may be unlocked. for turning movement by actuating I the double-acting cylinders 65to lift the wedges 63,

whereby to release the adjustment ring 47.

LOCK SYSTEM ACTUATORS There are at least two hydraulic units 66 for each wedge 63. These units can be used with or without spring units 67. If only theformer are provided, preferably three hydraulic units per wedge 63 are used. But, if spring units 67 are employed,preferably two hydraulic ,units 66 and three spring units 67 are employed.

For simplicity of illustration, the: segmented wedging ring is shown as having only two wedges 63, each having two hydraulic units 66 (FIG. 2) and three spring units 67. In a seventy-four inch crusher, the segmented wedging ring would have more wedges, say around six. Each wedge .would be actuated as described above.

'Eachspring unit has a pin 69 (FIG. 5) bearing against the upper surface 71 of the associated wedge 63 and passing through a hole 73 in a flange 75 of the bowl 49.

Each pin 69 has a reduced diameter portion 76 passing through a pressure plate 77, mounted above flange 75 by a pair of stud bolts 75a. The pin 69 passes through Belleville spring washers 79 which are compressed between the pressure plate 77 and a shoulder 81 of the pin 69 by nuts 75b on the stud bolts 75a. This applies downward pressure on the associated wedge 63 to lock threads 45 into threads 43 of the bowl carrier 41.

The pistons 78 of the double-acting cylinders 65 (FIG. 4 and have rods 80 projecting upward against beams 82 and downward against the wedges 63. Rods 80 are not attached to the wedges or the beams 82, but only bear against them. Capscrews 84 (FIG. 10) pass through the beams, plates 88 and flange 75 of how] 49, and are threaded into tapped bores in the wedges 63. Capscrews 86 (FIG. 11) bolt hydraulic cylinders 65 to flange 75 to take upward thrust. Seals 92 and 94 (FIG. 10) for the rods 80 are provided in the upper and lower ends of the cylinders, the latter end being plugs 96.

BOWL ADJUSTMENT MECHANISM A bowl clearance adjusting mechanism 90 (FIGS. 6 and 12) includes a double ended pawl 93 (FIG. 6) adapted to be moved against one of plural projections or cleats 95 fixed around the periphery of a cover 97 which is attached to bowl 49. The pawl 93 is pivotally mounted at 99 to the end of an arm 1120f bellcrank 101, which includes a sleeve 107 by which the bellcrank is pivotally mounted on a pin 103. The latter is fixed at its upper end to a base plate 100 on which the bracket is mounted. Plate 100 is bolted to the holddown ring 111 which is supported by the bowl carrier 41.

The bellcrank 101 includes an arm 110 (FIG. 8) which is attached to the lower end of the sleeve 107. The arm is pivotally connected to a double-acting booster cylinder 109 which is mounted on base plate 100.

To adjust the size of the opening 85 (FIG. 1) between the bottom surface 87 of the liner 51 and the top surface 89 of the crushing mantle 91, the pistons 78 are first retracted, drawing up the wedges 63 thereby releasing the bowl 49. Then mechanism 90 is actuated (in a manner to be described) to reciprocate pawl 93 to incrementally advance the cover 97 and thus the bowl 49 in a desired direction. This action will either raise or lower the bowl 49 depending on the direction of rotation. Then the bowl is locked in position.

BELLCRANK CONTROLS Bellcrank 101, being journaled on pin 103, is free to move through an arc equally on each side of a radius projecting to the center of the crusher. The are is limited to the stroke of piston of cylinder 109.

Arm 112 of bellcrank 101 has an outwardly extending portion formed with a tapered socket 114 (FIGS. 6 and 12). Fitting in socket 114 is a second socketed arm 116 pivoted at 117 to arm 112. The arm 116 is sufficiently loose within the socket 114 as to move far enough to actuate hydraulic valves 120 (FIGS. 6 and 12) on each side of the arm. These valves are connected (not shown) to the ends of cylinder 109 so as to cause the piston of the cylinder to reciprocate as the valves 120 are alternately operated. The valves receive fluid from a pump P (FIG. 12).

Two electric solenoids 128 are mounted on the arm 112 with their plungers connected to the arm 116. A

manual lever 124 (FIG. 6) of any desired length is insertable into the socketed arm 116 and a handle 126 (FIGS. 6 and 9) is provided.

Two solenoids 130 (FIG. 6) are pivotally mounted on brackets welded to bracket 105. The solenoids selectively set the pawl 93 for driving the bowl either for upward adjustment or downward adjustment. Each solenoid 130 includes a compression spring 132, a winding 140, a movable, headed core 142 and a tubular guide 144. The compression springs 132 are compressed between and abut the cores 142 and headed rods 146. The latter are slidable in the guides 144 and are pivotally secured to the end portions of the pawl 93.

BOWL CARRIER HOLD DOWN MECHANISM The bowl carrier 41 (FIG. 1) is held tightly against the support ring 33 by the holddown ring 111. The latter has a vertical flange 113 which is connected by adjustable hold-down rods 115 to cylinder brackets 118 (FIGS. 1 and 3) which carry the rod ends 119 of a pair of cylinders 121. The blind ends of the cylinders are supported on the underside of the flange 37.

Fluid is supplied to the cylinders 121 through a riser pipe 123, from a circular supply pipe 125. A series of charged accumulators 127 maintain the required pressure to actuate the cylinders downwardly, thereby drawing down the ring 111.

The ring 111 (FIGS. 1 and 4) has a bearing engagement with carrier bowl 41 by means of rings 129 of non-metallic bearing materialwhich are recessed into the inner periphery of the ringlll, and a ring 131 of non-metallic bearing material recessed into the outer edge of the bowl carrier 41. The bearing rings may be made of Micarta. Ring 131 is thick enough to provide clearance 159 (FIG. 4) between the upper face of the bowl carrier 41 and the lower face of the ring 111. An annular member 165 (FIG. 1) of the non-metallic bearing material is provided between the bowl 49 and the bowl carrier 41.

Under normal crushing conditions, the upper assembly of the crusher, including the bowl carrier 41 and all its companion parts, will not move while the crusher head 13 gyrates. However, when non-crushable objects pass through the crusher, or if the crusher is improperly operated, the upper assembly can lift away from support ring 33 at the high point of the camming member 17, against the resistance of the cylinders 121. This lifting action urges the bowl carrier 41 to creep circumferentially relative to the support ring 33.

In other cone type crushers, a means of positively locking against this creeping is usually employed. I-Iowever,'the force urging creeping can become so enormous that heavy steel castings and restraining parts are broken. My improved design, as disclosed herein, allows creep to occur when necessary, because bowl carrier 41 can slide under ring 111 and migrate around the ring 33 as the forces dictate. The non-metallic rings 129 and 131 prevent galling, because metal does not slide against metal.

CRUSHER HEAD CONSTRUCTION A machined surface of the mantle 91 (FIG. 1) is clamped tightly against the body of the head 13 by a self-tightening clamping member 152, screwed into a tapped socket member 154 secured to the head 13 by capscrews 156. A frustoconical cap 158 is secured by a screw 160 and a tapped plug 162 to the clamping member 152. A washer-like wedging ring 166 is pressed by the member 152 against the mantle 91. A frustoconical, washer-like boss 168 is pinned to the top of the body of the head 13. It has a square hole to receive a special tool to turn the member 152 when changing the mantle 91.

OPERATION In operation, the material to be crushed enters the top opening 133 and descends into the crushing chamber opening 85. It is shattered several times as it passes between liner 51 and mantle 91. It is sized by the closest approach position of mantle 91 to liner 51. This spacing only varies when adjustment is made or wear occurs. Adjustment can be effected by operating the mechanism 90 (FIGS. 6 and 12) which has three modes of operation. One is completely manual without hydraulic booster assistance (in case of malfunction of hydraulics). The second is hydraulic actuation with minute manual effort applied to the arm 1 16. The third is electric control either at the crusher or from a remote station.

For fully manual operation, the operator directs hydraulic pressure under the pistons 78 which lift the wedges 63, thereby releasing the bowl 49. Lever 124 is inserted into arm 116, and the operator manually shifts pawl 93 back and forth to turn the bowl assembly by manual power. After the desired size crushing chamber is attained, the wedges 63 are again forced down to lock the bowl in place.

In the second mode of operation, pressure is applied under the pistons 78 to free the bowl. The operator manually sets the pawl 93 for turning the bowl in the desired direction. He then moves the handle 126 back and forth to actuate the valves 120 which supply fluid to cylinder 109 as to cause it to reciprocate pawl 93. The operator may reverse setting of the pawl 93 if he goes past the desired height of the bowl. When the adjustment is attained, the pistons 78 are thrust downward to lock the bowl in position.

In the third mode of operation, electric controls (not shown) from a control console at any remote or nearby station are utilized. A selected directional button (not shown) first actuates the pistons 78 upward, then the proper solenoid 130 is actuated to flip the pawl 93 to the desired setting. Then solenoids 128 are alternately energized to swing the arm 116 alternately against the valves 120 to cause cylinder 109 to reciprocate the pawl93. Operation can be single cycle or automatic repeating until stopped.

Finally, after adjustment, the pawl 93 is swung clear of cleats 95 so that they do not interfere with emergency creeping of the bowl.

More than one bowl adjustment mechanism 90 may be used. Two assemblies 180 apart will provide balanced torque. Multiple assemblies will be interconnected to work in harmony.

The filler block 60, previously mentioned, is used with medium or fine liners 51, but of course is not necessary with a coarse liner, which is thick enough to directly engage the bowl 49.

I claim:

I. In a rock crusher,

bowl means including a liner and an annular liner support, l

a discontinuous, radially expansible, annular threaded ring having a thread on the periphery thereof and engaging and adapted to press downwardly on the liner support,

a carrier nut surrounding the threaded ring,

a wedging ring engaging the threaded ring and adapted to press the threaded ring outwardly into jammed engagement with the carrier nut,

and thrusting means carried by the liner support and adapted to press the wedging ring downwardly against the threaded ring to expand the threaded ring.

2. The rock crusher of claim 1 wherein the threaded ring comprises a plurality of segments.

3. The rock crusher of claim 1 wherein the liner support has peripheral notches,

the threaded ring being expansible radially in the notches and the wedging ring being movable longitudinally in the notches.

4. The rock crusher of claim 3 wherein the thrusting means includes plungers engaging the wedging ring and pressing means pressing the plungers downwardly.

5. The rock crusher of claim 4 wherein the pressing means includes a plurality of cupped spring washers.

6. The rock crusher of claim 1 including a base having a way,

the carrier nut being mounted rotatably on the way, and clamping means clamping the carrier nut to the way.

7. The rock crusher of claim 6 wherein the way is hardenable and is separate from the remainder of the base.

8. The rock crusher of claim 6 wherein the clamping means has a hard bearing material engaging the nut.

9. In a rock crusher,

a base having a top flange,

an annular way,

releasable fastening means securing the way to the top flange,

and bowl means having a downwardly facing annular groove resting on the way.

10. In a rock crusher,

a base, an annular way,

bowl means having a downwardly facing annular groove resting on the way,

and frictional clamping means locking the bowl means to the way during normal operation forces and permitting movement of the bowl means along the way upon occurrence of abnormally high forces. I

11. The rock crusher of claim 10 wherein the bowl means includes a bowl carrier resting on the way,

and rotative adjustable means locking the bowl meansto the carrier.

12. In a rock crusher,

bowl means,

carrier means,

I and fastening means including springs securing the bowl means to the carrier means,

the fastening means including female threads on the carrier means, a segmented threaded ring adapted to. be radially expanded into locked engagement with the carrier means and having a wedging surface, a wedging ring engaging the threaded ring, and thrust members urged by the springs in a direction tending to expand the threaded ring.

13. In a rock crusher, 1

base means,

bowl means,

a carrier nut mounted on the base means,

threaded means secured to the bowl means and screwed into the carrier nut,

ratchet means'on the bowl means,

pawl means movably mounted on the base means,

fluid cylinder means for driving the pawl means,

and manually operable lever means for driving the pawl means independently of the cylinder means.

14. in a rock crusher,

a gyratory head,

a nut releasably mounted on the head,

a wedging member having a thread shank screwed into the nut,

a wedging ring engaged by the wedging member,

and mantle means pressed against the head of the wedging ring.

15. In a rock crusher,

a bowl,

a wedge,

a beam connected to the wedge,

a double-acting cylinder secured to the bowl,

and a piston in the cylinder and having one end engaging the beam and the other end engaging the wedge.

16. The rock crusher of claim 15 including tie rod means connecting the beam to the wedge,

the tie rodmeans extending through the bowl support.

17. The rock crusher of claim 16 wherein the tie rod means comprises a pair of capscrews.

18. In a rock crusher,

base means,

externally threaded bowl means, v

an internally threaded bowl carrier means mounted on the base means,

reversible ratchet means fixed to the bowl means,

a reversible pawl,

arm means mounted pivotally on the base means and carrying the pawl for moving the pawl to move the ratchet means and the bowl means relative to the bowl carrier means,

means for selectively setting the reversible pawl means for turning the bowl means in either direc-' tion,

and oscillatory drive means for moving the arm means,

the drive means including a power drive for moving the arm means,

the drive means also including a selectively operable,

manually operable arm connected to the arm means for moving the arm means independently of the power drive.

19. The rock crusher of claim 18 including actuator means mounted on the arm means for actuating the power drive and actuated by the arm when the arm is moved manually.

20. The rock crusher of claim 19 wherein the power drive is a double-acting cylinder and the actuator means-includes valve means on the arm means and valve actuating means on the arm.

21. The rock crusher of claim 20 wherein the valve actuating means includes solenoid means.

22. The rock crusher of claim 9 wherein the top flange has an annular, upwardly facing V-groove and the annular way has a lower portion complementary to and fitting in'the groove. 

1. In a rock crusher, bowl means including a liner and an annular liner support, a discontinuous, radially expansible, annular threaded ring having a thread on the periphery thereof and engaging and adapted to press downwardly on the liner support, a carrier nut surrounding the threaded ring, a wedging ring engaging the threaded ring and adapted to press the threaded ring outwardly into jammed engagement with the carrier nut, and thrusting means carried by the liner support and adapted to press the wedging ring downwardly against the threaded ring to expand the threaded ring.
 2. The rock crusher of claim 1 wherein the threaded ring comprises a plurality of segments.
 3. The rock crusher of claim 1 wherein the liner support has peripheral notches, the threaded ring being expansible radially in the notches and the wedging ring being movable longitudinally in the notches.
 4. The rock crusher of claim 3 wherein the thrusting means includes plungers engaging the wedging ring and pressing means pressing the plungers downwardly.
 5. The rock crusher of claim 4 wherein the pressing means includes a plurality of cupped spring washers.
 6. The rock crusher of claim 1 including a base having a way, the carrier nut being mounted rotatably on the way, and clamping means clamping the carrier nut to the way.
 7. The rock crusher of claim 6 wherein the way is hardenable and is separate from the remainder of the base.
 8. The rock crusher of claim 6 wherein the clamping means has a hard bearing material engaging the nut.
 9. In a rock crusher, a base having a top flange, an annular way, releasable fastening means securing the way to the top flange, and bowl means having a downwardly facing annular groove resting on the way.
 10. In a rock crusher, a base, ''an annular way, bowl means having a downwardly facing annular groove resting on the way, and frictional clamping means locking the bowl means to the way during normal operation forces and permitting movement of the bowl means along the way upon occurrence of abnormally high forces.
 11. The rock crusher of claim 10 wherein the bowl means includes a bowl carrier resting on the way, and rotative adjustable means locking the bowl means to the carrier.
 12. In a rock crusher, bowl means, carrier means, and fastening means including springs securing the bowl means to the carrier means, the fastening means including female threads on the carrier means, a segmented threaded ring adapted to be radially expanded into locked engagement with the carrier means and having a wedging surface, a wedging ring engaging the threaded ring, and thrust members urged by the springs in a direction tending to expand the threaded ring.
 13. In a rock crusher, base means, bowl means, a carrier nut mounted on the base means, threaded means secured to the bowl means and screwed into the carrier nut, ratchet means on the bowl means, pawl means movably mounted on the base means, fluid cylinder means for driving the pawl means, and manually operable lever means for driving the pawl means independently of the cylinder means.
 14. In a rock crusher, a gyratory head, a nut releasably mounted on the head, a wedging member having a thread shank screwed into the nut, a wedging ring engaged by the wedging member, and mantle means pressed against the head of the wedging ring.
 15. In a rock crusher, a bowl, a wedge, a beam connected to the wedge, a double-acting cylinder secured to the bowl, and a piston in the cylinder and having one end engaging the beam and the other end engaging the wedge.
 16. The rock crusher of claim 15 including tie rod means connecting the beam to the wedge, the tie rod means extending through the bowl support.
 17. The rock crusher of claim 16 wherein the tie rod means comprises a pair of capscrews.
 18. In a rock crusher, base means, externally threaded bowl means, an internally threaded bowl carrier means mounted on the base means, reversible ratchet means fixed to the bowl means, a reversible pawl, arm means mounted pivotally on the base means and carrying the pawl for moving the pawl to move the ratchet means and the bowl means relative to the bowl carrier means, means for selectively setting the reversible pawl means for turning the bowl means in either direction, and oscillatory drive means for moving the arm means, the drive means including a power drive for moving the arm means, the drive means also including a selectively operable, manually operable arm connected to the arm means for moving the arm means independently of the power drive.
 19. The rock crusher of claim 18 including actuator means mounted on the arm means for actuating the power drive and actuated by the arm when the arm is moved manually.
 20. The rock crusher of claim 19 wherein the power drive is a double-acting cylinder and the actuator means includes valve means on the arm means and valve actuating means on the arm.
 21. The rock crusher of claim 20 wherein the valve actuating means includes solenoid means.
 22. The rock crusher of claim 9 wherein the top flange has an annular, upwardly facing V-groove and the annular way has a lower portion complementary to and fitting in the groove. 